Micellar solutions as reaction media

Toxic and mutagenic effects of chromium(VI). A review

Removal of chromate anions by micellar-enhanced ultrafiltration using cationic surfactants☆

Removal of hexavalent chromium by nanofiltration

Phosphate removal from water by red mud using crossflow microfiltration

Micellar-enhanced ultrafiltration can be used to remove multivalent anions or cations from aqueous streams. In the removal of chromate ions (CrO), the cationic surfactant hexadecylpyridinium chloride is added to the solution, and the chromate ions preferentially adsorb at the surface of the highly charged surfactant micelles. The solution is processed by ultrafiltration, using a membrane with pore sizes small enough to block the passage of the micelles and adsorbed ions. The permeate solution has a chromate concentration less than 0.1% that in the original stream. A new equilibrium model, combining the simple two-phase polyelectrolyte theory of Oosawa with thermodynamic activity, material-balance, and charge-balance equations, successfully correlates ultrafiltration and equilibrium dialysis results for chromate solutions.

Micellar-enhanced ultrafiltration of chromate anion from aqueous streams

In micellar-enhanced ultrafiltration (MEUF), solubilization of organic solutes in micelles, combined with ultrafiltration of these micellar solutions, leads to the removal of dissolved, low molecular weight organic compounds from water. The permeate from MEUF contains the organic solute at concentrations equal to the unsolubilized solute concentration in the rejected (retentate) solution. Therefore, the equilibrium solubilization of the solute dictates the permeate purity or rejection of the solute by the membrane. The semiequilibrium dialysis method has been used to investigate the equilibrium solubilization of o-, m-, and p-cresol by aqueous solutions of 1-hexadecylpyridinium chloride, throughout a range of concentrations of the cresols and the surfactant. The apparent solubilization constant, K = X/sub c//(concentration of unsolubilized cresol), has been correlated with X/sub c/, the mole fraction of cresol in the micelle.

S. N. Bhat

Papers

Micellar-enhanced ultrafiltration of chromate anion from aqueous streams

Solubilization of cresols by 1-hexadecylpyridinium chloride micelles and removal of cresols from aqueous streams by micellar-enhanced ultrafiltration